In the field of self-adhesive labels, it is customary to coat fully all or at least most of the areas of a label with adhesive material. Further, the adhesive materials are normally classified as permanent type adhesives or removable adhesives. When a label is fully coated with a permanent type adhesive, and is applied to a product, it normally cannot be removed without destroying either the label or the product upon which it is mounted. On the other hand a coating of a removable adhesive material will permit the label to be peeled off, and re-applied.
The nature of an adhesive, whether permanent or removable, is often specified by the force required to peel (peel force) a one inch sample strip at right angles from a stainless steel surface to which it has been adhered. Standards and procedures for measuring peel forces have been established by the Pressure Sensitive Tape Council, and the peel forces as used herein relate to tests made pursuant to such standard procedures. The designation "permanent adhesives" is normally applied to adhesives having peel forces in the order of 3 pounds or more, while adhesives having a peel force of less than about 2 pounds are normally referred to as removable adhesive coatings.
More generally, when the entire system including the label, adhesive, and underlying surface such as a product box, are considered, a permanent adhesive is one wherein a full coating will prevent removal of the label without impairing the structural integrity of the label or the underlying surface; while a removable label is one which will not affect the structural integrity of the label or the underlying surface, but which may be peeled back and re-used. Further, the strength of the label may be increased by forming the face stock from which the label is made from material containing long fibers, or by pre-coating the label surface with a high strength plastic coating. Using such high strength labels, a higher peel force for the adhesive may be tolerated, with the labels still being removable.
One object of the present invention is to provide a label using a single type of adhesive which will provide a permanent bond on one area of the label and a weaker, removable adhesive on other areas of the label.
It has previously been proposed to have patterns of adhesive applied to tapes or the like without fully covering the area, or with a thicker layer on one portion of the surface than on another area. Typical prior U.S. patents of this type include the following:
J. V. Bauer et al. U.S. Pat. No. 2,294,347, g. Aug. 25, 1942 PA1 H. A. Evans, U.S. Pat. No. 2,349,710, g. May 22, 1944 PA1 L. B. Schrans, U.S. Pat. No. 2,721,810, g. Oct. 25, 1955 PA1 A. G. Patchell, U.S. Pat. No. 2,940,868, g. June 14, 1966 PA1 T. F. Banigan, Jr., et al., U.S. Pat. No. 3,039,893, g. June 19, 1962 PA1 N. Warshens, U.S. Pat. No. 2,684,316, g. July 20, 1954 PA1 C. W. Vogt, U.S. Pat. No. 2,867,317, g. Jan. 6, 1959
However, these patents do not solve the problem of providing a label having a permanent bond in one area of the label and reclosable self-adhesive properties in another area of the label. Accordingly, an important object of the invention is to provide such a label.